Common welding-type power supplies used in high temperature metal processing systems such as welding or plasma cutting systems generally include a power supply connected by a cable to a torch at which the welding or cutting operation takes place. In manual, hand-operated systems the torch is typically contained in an insulated handle that is held and guided by an operator. In automated systems, the movement of the torch is typically performed using a cutting table that is controlled by a computer using CNC. In both manual and automated systems, the torch is detachably connected to the cable, and the cable is detachably connected to the power supply. Depending on the system performance desired for a particular welding or cutting operation, the system can be assembled from various combinations of power supply, cable, and torch. Common performance factors considered when selecting a power supply include the costs of purchase, operation, and maintenance of the power supply, the ability of power supply to remain within an operational temperature range, the mobility of the power supply, and the environment in which the power supply will be used.
A significant factor in the selection of a power supply is the cost relating to the purchase, operation, and maintenance of the power supply. The purchase price and repair costs are in part related to the effort required to assemble and disassemble the power supply. Maintenance costs are also increased because the time required for repair is unduly long, as increased repair costs reflect a greater amount of labor, and because of the extended down time during which the power supply is not available for service. The operational costs are also affected by the efficiency of the power supply, which is degraded, for example, when the power supply operates at an excessively elevated temperature. It is therefore desirable that the power supply operate efficiently at low operational cost while also being affordable to purchase and maintain.
Another factor considered in the selection of a welding-type power supply is the ability of the device to remove heat generated by internal components. Due to the large amounts of power handled by the power supply, internal transformers, resistors, and other heat-generation components raise the overall temperature of the power supply. Excessive heat in the power supply can lead to component damage, reduced efficiency of the system, and the tripping of temperature sensors that limit duty cycle. These conditions represent failures of the power supply because the device is no longer operational until repaired or sufficiently cooled and reset, or limits operating time until components are cooled and reset. Such outages represent lost shop time and adversely affect efficiencies and throughput capacities.
Many common power supplies utilize a forced-air cooling system to cool internal components. However, existing forced-air cooling systems require a power supply layout in which the heat-generating parts are distributed sufficiently far apart from each other to permit the inflow and circulation of cooling air. The layout of such systems leads to a large power supply size, which in turn limits the mobility of the power supply. Often, the power supply must be transported with other equipment to the worksite or carried by hand, and a large, bulky, or heavy power supply is more difficult to transport. Furthermore, a layout in which internal components are spaced apart to promote circulation leads to more complicated manufacturing and repair procedures, as most internal components must be separately mounted to the power supply framework and hardwired into the device. Such designs lead to extra system costs because of the additional manufacturing and wiring required, and to extra repair costs because of the additional time required to identify and replace failed or defective internal components. Additional costs also result because the complexity of such systems requires additional repair time during which the system is not useable. It is therefore desirable that the power supply be capable of maintaining a sufficiently low operational temperature while minimizing power supply size and having a simplified component layout.
Yet another factor considered in the selection and design of a power supply is the environment in which the power supply will be used. Welding and cutting operations can be performed in a wide variety of environments and harsh conditions, such as outdoors, in high humidity or rain, and in atmospheres that contain corrosive, conductive, potentially flammable, or other dust-type contaminates. Existing forced air cooling systems impel moisture and contaminated air through the power supply and, due in part to the distribution of heat-generating components in such systems, the entrained moisture and contaminants are distributed throughout the inside of the power supply. Over time, the moisture and contaminants affect and/or accumulate upon component surfaces within the power supply, eventually reducing the ability of those components to remove excessive heat and possibly corroding or otherwise degrading the performance of the components or cause electrical shorting of components. It is therefore desirable that the power supply be capable of operating in a wide variety of environments at operational temperature while minimizing the exposure of internal components to moisture and other environmental contaminants.
In view of the foregoing, what is needed is a cooling system for a power supply that has low system and operational costs, is capable of maintaining an operational temperature within certain boundaries, has minimal size and a simplified design, and is capable of performing in a variety of environments while minimizing the entry of moisture and contaminants into the power supply. A first object of the invention is to provide a power supply that operates efficiently at low operational cost while also being affordable to purchase and maintain. Another object of the invention is to provide a power supply that is capable of maintaining an operational temperature while simultaneously minimizing power supply size and promoting a simplified component layout. Yet another object of the invention is to provide a power supply capable of operating in a wide variety of environments at reasonable operational temperatures while minimizing the exposure of internal components to moisture and other environmental contaminants.